Other implementations allow building from Containerfile / Dockerfile: https://java.testcontainers.org/features/creating_images/
public GenericContainer dslContainer = new GenericContainer(
new ImageFromDockerfile()
.withFileFromString("folder/someFile.txt", "hello")
.withFileFromClasspath("test.txt", "mappable-resource/test-resource.txt")
.withFileFromClasspath("Dockerfile", "mappable-dockerfile/Dockerfile"))